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Fencer Intel
critical 9.8

CVE-2021-26084 kev+ ransomware in the critical feed json

In affected versions of Confluence Server and Data Center, an OGNL injection vulnerability exists that would allow an unauthenticated attac…

published 5y ago modified 4mo ago also EUVD-2021-12905

cvss
9.8
version 3.1, CNA
cisa kev
Exploited
added 2021-11-03, used in ransomware
epss
100.0%
EPSS 100.0% chance of exploitation in 30 days, percentile 99.9%
public exploits
2
Metasploit and Exploit-DB, plus a Nuclei check

Summary

In affected versions of Confluence Server and Data Center, an OGNL injection vulnerability exists that would allow an unauthenticated attacker to execute arbitrary code on a Confluence Server or Data Center instance. The affected versions are before version 6.13.23, from version 6.14.0 before 7.4.11, from version 7.5.0 before 7.11.6, and from version 7.12.0 before 7.12.5.

Patch / fix

cisa required action Apply updates per vendor instructions.

  • Atlassian Confluence Server 6.13.23, 7.4.11, 7.11.6, 7.12.5
  • Atlassian Confluence Data Center 6.13.23, 7.4.11, 7.11.6, 7.12.5

Is CVE-2021-26084 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Timeline

  1. First public exploit (Metasploit exploit/multi/http/atlassian_confluence_webwork_ognl_injection)
  2. Published
  3. Added to CISA KEV
  4. CISA patch deadline
  5. CISA SSVC: exploitation active

Known exploited

Added
5y ago
Patch by
2021-11-17 (4y ago)
Ransomware
Known to be used in ransomware campaigns
Required action
Apply updates per vendor instructions.
Vendor, product
Atlassian, Confluence Server and Data Center
CISA name
Atlassian Confluence Server and Data Center Object-Graph Navigation Language (OGNL) Injection Vulnerability

ATT&CK techniques

How it is exploited and what it leads to, in MITRE ATT&CK terms.

  • T1059 Command and Scripting Interpreter primary impact
  • T1496 Resource Hijacking secondary impact

kev release 2025-07-28, att&ck v16.1. KEV to ATT&CK mappings by the MITRE Center for Threat-Informed Defense (Mappings Explorer, Apache-2.0). © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. Terms of use

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
yes
Technical impact
total
Assessed
10mo ago

Exploit prediction

100.00% chance of exploitation in the next 30 days, higher than 99.9% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • Atlassian Confluence Server
  • Atlassian Confluence Data Center

Classification

Weakness
  • CWE-917 Improper Neutralization of Special Elements used in an Expression Language Statement

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.